D.P.
Hi M.,
My son would (if we let him) play Wii until his eyes were as big as pies! lol
It's good that he likes Wii Fitness and Wii Sports as much as the more "couch potato-y" games. And with this cold/snowy weather, he is getting some exercise at least.
30-45 minutes per day (after his schoolwork is done) is OK with us. On the weekend, he may play a little more, but it is broken into smaller chunks of time. I don't allow him to play video games before school.
There are times when Mario Kart Wii gets him extremely frustrated and angry--we have to watch that O. much more closely!
IMO, if your son plays during your little O.'s "nap time" and it keeps the flow going in your house, then that's great. Maybe he could do something more O.-on-O. with you every other day? I know in our house, the video games seem to go in spurts--some weeks he barely touches it and other weeks he wants to play every day!